LAUSANNE, March 31. /TASS/. Talks between Iran and P5+1 group of international mediators may continue far into the night, French Foreign Minister Laurent Fabius told journalists on Tuesday.

"We are moving forwards but the talks may continue well into the night," he said. "The process is long and difficult."

Representatives of a number of delegations said earlier that they were prepared to stay in Lausanne as long as it might take.

Iran and the P5+1 group (the five permanent members of the United Nations Security Council and Germany) are negotiating a document on political principles that is to be supplemented by technical details by late June to ultimately become a comprehensive agreement.